Method of covering articles



Jan. 24, 1956 R. L. NOWAK 3 METHOD OF COVERING ARTICLES Filed Nov. 23, 1953 2 Sheets-Shet 1 IN VEN TOR.

m. 24, wsa

Filed Nov. 23, 1953 R. L. NOWAK 2333 6554 METHOD OF COVERING ARTICLES 2 Sheets-Sheet 2 usual JLILZ v United States Patent 6 METHOD OF COVERING ARTICLES Roger L. Nowak, West Boylston, Mass, assignor to Van Erode Milling Co., Inc., Clinton, Mass, a corporation of Massachusetts Application November 23, 1953, Serial No. 393,676

1 Claim. (Cl. 12-147) The present invention relates to the manufacture of shoe heels, and more particularly to the manufacture of that type of heels in which a wooden core has its sides and breast surfaces covered with sheet material.

Heels having wooden cores are usually covered by the shoe manufacturer with thin leather or fabric matching that used in the shoe upper, although other and contrasting materials are sometimes used, for instance thin Celluloid. In most of the constructions heretofore in use, the cover is composed of two sections, one being applied to the curved rear and lateral surfaces of the core and the other to the breast surface thereof. In other words, the cover for the breast surface of the heel is a separate part independent from the covering of the outer heel surface. This usual method covering the core provides so insecure a union of the outer and breast coverings as to bring about separation of the covering elements at their points of junction, with consequent gapping and exposure of the core, often followed by fraying of the raw edges and a resultant unsightly appearance.

To overcome the difficulties so encountered, it has been proposed heretofore to provide an endless or seamless covering of Celluloid for these wooden cores. In applying such cover to a wooden core, a cement must be put upon the latter and the cover placed in position after having been suitably softened. In the operation, the operator who applies the cover must handle the sticky cores, which hampers his speed and may cause transfer of the cement from the cores to the display surfaces of the covers. in any event, the operation of covering heels in this manner has been a slow One.

It has also been suggested to provide seamless cover blanks in the form of a swollen gel obtained by molding various colloidal substances. Such blank, when placed upon a core, is shrunk, for instance, by heat to cause it to come into contact with the surfaces of the core, the blank being thereafter subjected to heat and pressure, being thus caused to be pressed against the core, a suitable film of cement being interposed between the blank and the core. While this method overcomes some of the difiiculties experienced in practising the processes above referred to, it is not practical from the standpoint of factory production, since it involves expert, careful, unduly prolonged and expensive operations.

The principal object of the present invention is to provide an improved method of covering heels, whereby it is possible by factory methods and at a reasonable cost to produce heels having seamless coverings, and which overcomes all' the difficulties heretofore 'met with in the methods previously practised.

With this and other objects in view, which will more fully appear as the nature of the invention is better understood, and in accordance with the present invention, a sheet of thermoplastic material of suitable size and thickness, clamped between rings, is placed above an inverted heel core which rests upon a support on a fiat surface. The sheet is thereupon heated to a softening point appropriate to drawing and shaping. The clamping means 2,731,654 Patented Jan. 24, 1956 moves by gravity, as the sheet is being softened, toward and into contact with said flat surface, and causes, in cooperation with the heel core, the plastic sheet to assume a frusto-conical shape, which forms, in conjunction with said fiat surface, a closed hollow shell or blank around the core and support. A vacuum or partial vacuum is then created in the shell or blank, which causes the blank to assume the conformation of the heel core, a film of cement on the latter forming a bond between the blank and the core.

In order that the invention may be more fully understood, reference is made to the accompanying drawings, showing one of the many possible devices for carrying out the improved method, and in which:

Figure l is a front elevation of the core of a heel, for purposes of illustration a Cuban heel;

Fig. 2 is a section taken on line 22 of Fig. 1;

Fig. 3 is a front elevation, partly in section, more or less diagrammatic, of an apparatus for carrying out the improved method;

Fig. 4 is a top plan view of the core support;

Fig. 5 is an elevation similar to the one shown in Fig. 3, the blank being formed into frusto-conical form; and

Fig. 6 is a similar elevation, showing the blank in its final shape.

The heel covering comprises a suitable thermoplastic material, initially in sheet form of a suitable size and thickness, depending on the size of the heel core to be covered and on the desired thickness of the covering to. be applied. The material is, preferably, supplied to the manufacturer in strip form, to be cut by the manufacturer to the desired sheet size.

In the case illustrated in the drawings, a Cuban heel core 10 is shown, but only for purposes of illustration, the method being applicable to other shapes just as well, in fact to objects other than heels. A suitable cement, capable of being activated by heat or by some of the components of the thermoplastic material used, or by both, is applied to the bottom 10', the concaved breast 11, the sides 12, the curved back 13 and a strip 14 of the heel attaching face 15 of the core, adjacent the periphery of said face. Preferably, the cement is applied to a large number of heels in advance and allowed to dry, since such procedure obviates handling of sticky cores by the operator who places the cores on the cover applying apparatus.

The cover applyingapparatus consists of a vacuum chamber 16, which is in communication with a vacuum source, such as an air pump (not shown), the communication being controlled by a suitable means (not shown), to create a vacuum in the chamber or to cut off the vacuum source, as desired. The flat top 17 of the chamber is covered by a rubber or like mat 18, and through this mat and the chamber top extend registering openings H and 26, respectively. To the chamber top 17 is fixed a heel support 21, in the form of a block, through which extends a channel 22, in communication with the registering openings 19 and 20 above referred to. The channel 2 runs through the entire height of the support 21, that is from its base 23 to its inclined top 24. The contour of the horizontal cross section of the support 21 is similar to the contour of the. heel attaching face 15. of the heel core but it is smaller, as clearly shown in Figs. 3, 5 and 6, so that the strip 14 adjacent the periphery of said heel attaching face is left free when the core is mounted on said support. In the inclined top 24 of the core is formed a plurality of grooves 25, which run from the channel 22 to the perimeter of said top, so that with a heel core in position on the support, as shown in Figs. 3, 5 and 6, vacuum may be applied to the exposed faces of said core and said support once the cover blank, in conjunction with 3 the vacuum chamber top, forms a closed chamber as shown in Fig. 5.

The heel core is adapted to be attached to the support 21 in any suitable manner with its heel attaching face 15 resting on the inclined top 24 of said support. The attaching means, not shown, is so arranged that tie strip 14 of the heel attaching face of the core is left free. When a core is mounted on the heel support 21 (Figs. 3, 5 and 6), its breast 11 is arranged at an angle to the vertical plane passing through the support. The purpose of this arrangement will be described hereinafter.

A suitable distance above the bottom i of a core, when attached to the heel support 21, is disposed a heater 26 of any suitable type, for instance an electric heater. Means, not shown, are provided for varying the distance between the heater and the heel core so as to enable the operator to change the heating efiiect of the heater, and/ or provision may be made for varying the heat output of the heater.

The plastic sheet 27 is clamped between rings 2%, heavy enough to carry with them and thereby stretch the sheet when the latter is heated sufficiently so that its material becomes plastic and moldable and the clamping means moves by gravity toward the chamber top 17. The lower one of the rings is provided on its under-face with a ridge 29, having a narrow bottom edge 30, which is adapted to bear against the rubber mat 18 on the vacuum chamber. Owing to the weight of the clamping means, a substantially airtight joint is provided between said clamping means and the rubber mat when the ridge 29 of the clamping means contacts with said mat, the vacuum, created as hereinafter described, drawing; the clamping means into airtight fit with said mat. The diameter of the clamping means exceeds considerably the dimensions of the heel attaching face of the heel core, whereby the sheet 27, initially resting on the bottom 19 of a heel core (Fig. 3), is formed into a cover blank 31 of frusto-conical shape (Fig. 5), when the heated sheet is stretched by the clamping means as the latter moves toward and into contact with the mat 18 on the vacuum chamber.

In practising the improved method, first of all the size and thickness of the plastic sheet 27 must be calculated for a given core to be covered. The size of the sheet depends mainly on the size of the heel, and the thickness of the sheet, and to some extent its size, is related to the thickness of the covering to be obtained. Next, the inclination of the core on the support 21 relative to the vertical plane passing through the support must be considered. In practice it has been found that when the core is disposed vertically, undesirable ridges and sometimes bulges are produced in the covering, because the breast 11 of the core extends vertically while the sides 12 and the curved back 13 thereof are located at angles differing greatly from that of the plane of the breast. By placing the breast at an angle to the vertical plane, its location approximates that of the sides and back, resulting in a smooth covering. The location and heating eifect of the heater 26 must then be taken into consideration, for the purpose of obtaining the proper drawing or forming temperature for the particular type of plastic material being processed, bearing in mind the size and thickness of the sheet 27 employed.

As shown in Fig. 3, the plastic sheet, clamped between the rings 28, is placed on top of the heel bottom It is then heated, whereby, due to the pliability or plasticity of the material thus obtained, the clamping means descends toward and into contact with the mat 18 on top of the vacuum chamber 16, thereby evenly stretching the said sheet and forming it, in cooperation with the heel core, into a blank 31 of frusto-conical shape (Fig. 5). As clearly shown in the drawings, this blank is closed at its base by the clamping means and the mat 18, coacting with the latter. A closed chamber is thus formed, in which the heel core is disposed. When now the vacuum producing mechanism is turned on, the still plastic and moldable blank is drawn into close contact with the bottom 10, breast l1, sides 12, curved back 13 and a limited area of the heel attaching face of the wooden core. It is also drawn against the exposed faces of the heel support 21, rubber mat 18 and the clamping means within the area of the closed chamber above referred to. The cementing material, is activated by the heat of the blank and/ or by some of the constituents of the plastic material, firmly attaching the covering to the core.

After the covering has been caused to adhere to the core, the surplus material, which does not adhere to the apparatus as no cement has been applied to the latter, is trimmed ofi.

The heating, blank forming, cover shaping and attaching operations take but a few seconds, are exceedingly simple and are, thus, capable of being carried out on a commercial scale.

It should be noted that, while herein the invention has been described in connection with the covering of a heel of particular configuration, it is not limited in scope to any specific shape or size of heel, or to the covering of any particular article. it should also be noted that, while the invention has been described in connection with providing an object, such as a heel, with a permanent covering in the form of a shell, the invention provides also a method of producing shells or hollow articles of any desired configuration by causing the blanks to take the shapes of forms and removing the shells from the forms, in which case, obviously, no cement would be used.

What I claim is:

The method of covering a heel core with a layer obtained from a sheet of thermoplastic material, which consists in mounting the heel core, provided with a film of cement on its breast, sides, curved back and along the peripheral portion of its heel attaching face, on a support so as not to cover the cement on said peripheral portion, said heel core being mounted on said support so that its breast extends at a substantial angle to a vertical plane passing through said support, placing the sheet clamped between rings on the heel core, applying heat to the sheet to elfeet plasticity in its material, stretching the plasticized sheet by the weight of said rings over the heel core below the supported face of the latter and closing the shell so formed around said core, and creating a partial vacuum in said shell whereby the latter is made to assume the conformation of the core and to adhere to the same by said film of cement.

References Cited in the file of this patent UNITED STATES PATENTS 1,946,770 Strongson Feb. 13, 1934 1,980,022 Whitehouse Nov. 6, 1934 2,088,352 Vierkotter July 27, 1937 2,210,509 Strauch Aug. 6, 1940 2,236,552 Ushakolf Apr. 1, 1941 

